Russia’s ties with the United States of America, languishing at post-Cold War lows ever since 2014 and Moscow’s expansionist designs in Ukraine, have come under renewed pressure since Wednesday in the immediate aftermath of President Joe Biden referring to President Vladmir Putin as a ‘killer’.

The epithet has rattled the Kremlin, though it would be presumptuous to argue that the latest kerfuffle between Washington and Moscow could ignite a new Cold War. It is nonetheless a measure of the critical build-up of tension that the Kremlin has summoned its ambassador in Washington to Moscow for talks.

The move to summon Anatoly Antonov to Moscow was announced shortly after President Biden accused his Russian counterpart of being a “killer”, and warned he would “pay a price” for alleged election meddling. Arguably, the language used was undiplomatic. In the net, the rupture in bilateral ties is palpable and the latest crisis has erupted exactly two months after the inaugural of Mr Biden.

Russia has denied as baseless the longstanding allegations of electoral meddling, which have been documented in the context of thwarting Hillary Clinton’s election in 2016. According to the Russian embassy in Washington, Antonov will leave the US on Saturday and will on his arrival in Moscow discuss “ways to rectify Russia-US ties, which are in crisis”.

Without mentioning the role of President Biden, the embassy said that “certain ill-considered statements of high-ranking US officials have put the already excessively confrontational relations under the threat of collapse”. Ties between the US and Russia have of late been under a cloud over the imprisonment of Kremlin critic Alexey Navalny.

In an interview to ABC News, President Biden was remarkably assertive. “You’ll see shortly,” he said when asked what consequences Russia would face for its alleged behaviour. He also described Putin as a man without a soul. When asked if he thought the Russian leader, who has been accused of ordering the poisoning of Navalny and other rivals, is a “killer”, Biden replied: “I do.”

The US President’s comments were aired as the Commerce Department tightened sanctions on some exports to Russia as punishment for Navalny’s alleged poisoning in August last year. The move will toughen restrictions originally put in place in response to the March 2018 poisoning of former Russian military intelligence officer, Sergei Skripal and his daughter in Salisbury, Britain, with a militarygrade nerve agent.

Altogether, it is a forbidding cocktail of intemperate language, alleged electoral meddling, and the current diplomatic blitz on the part of the Kremlin. And also, of course, the sharp slide in relations between the United States and Russia.